PARP1 inactivation increases regulatory T / Th17 cell proportion in intestinal inflammation. Role of HMGB1.

Inflammatory bowel diseases (IBD) are chronic relapsing disorders with increasing prevalence. Knowledge gaps still limit the possibility to develop more specific and effective therapies. Using a dextran sodium sulfate colitis mouse model, we found that inflammation increased the total number and altered the frequencies of leukocytes within colon mesenteric lymph nodes (cMLNs). Although the inflammation reduced the frequency of regulatory T (Treg) cells, their absolute numbers were increased. Increased frequency of colitogenic Th17 cells was also observed. Noteworthy, untreated mice lacking Poly(ADP-ribose)-Polimerase-1 functional gene (PARP-1KO) displayed higher frequency of Treg cells and lower percentage of Th17 cells in cMLNs. In colitic PARP-1KO mice the inflammation driven expansion of the Foxp3 Treg population was more pronounced than in WT mice. Conversely, colitis increased Th17 cells to a lower extent in PARP-1KO mice compared with WT mice, resulting in a more protective Treg/Th17 cell ratio. Consequently PARP-1KO mice developed less severe colitis with reduced expression of inflammatory cytokines. In ex vivo experiments PARP-1KO and WT CD11c dendritic cells (DCs) promoted naïve CD4 T cell differentiation differently, the former sustaining more efficiently the generation of Treg cells, the latter that of Th17 cells. Addition of HMGB1 B box or of dipotassium glycyrrhizate, which sequesters extracellular HMGB1, revealed a role for this alarmin in the regulation exerted by PARP-1 on the stimulating vs. tolerogenic function of DCs during colitis. Moreover, a higher percentage of CD11c DC from PARP-1KO mice expressed CD103, a marker associated with the ability of DC to induce Treg cells, compared with WT DC. Conversely, PARP-1KO DC were including a reduced percentage of CX3CR1+ DC, described to induce Th17 cells. These findings were observed in both splenic and colon lamina propria DC.

Von Willebrand Factor Activity Association With Outcomes After Transcatheter Edge-to-Edge Mitral Valve Repair.

Background: Residual mitral regurgitation (MR) is associated with worse outcomes after transcatheter edge-to-edge mitral valve repair (TEER). Shear stress induced by MR leads to altered von Willebrand factor activity (vWF:Act) and increased closure time with adenosine diphosphate (CT-ADP). Objectives: The purpose of this study was to investigate the use of CT-ADP to monitor MR during TEER and the association between the vWF, residual MR, and clinical events post-TEER. Methods: Sixty-five patients undergoing TEER were enrolled. CT-ADP was measured at baseline, after each clip deployment, 1 hour and 24 hours post-TEER. CT-ADP values were related to vWF:Act/vWF antigen (vWF:Ag) ratio at the same time points, and MR severity was assessed by echocardiography at 1 month. Combined events of all-cause mortality and heart failure hospitalizations were evaluated at 1 year. Results: At 1 month, 32 (49%) patients had residual MR > mild (of those, 14% had MR > moderate). There was no significant change in CT-ADP values during the procedure. However, CT-ADP significantly decreased 1-hour post-TEER (P < 0.001). Patients with corrected MR demonstrated an increase in vWF:Act/vWF:Ag ratio 1-hour post-TEER. Elevated baseline vWF:Act/vWF:Ag ratio and the periprocedural percentage changes of the vWF:Act/vWF:Ag ratio (1 hour post-TEER - baseline values) were associated with the combined clinical outcome. Conclusions: CT-ADP evolution in time was not quick enough to provide real-time monitoring of MR severity during TEER. However, vWF:Act/vWF:Ag ratio at baseline and its variations following the procedure were associated with clinical outcomes. Those findings will need external validation.

RBN-2397, a PARP7 Inhibitor, Synergizes with Paclitaxel to Inhibit Proliferation and Migration of Ovarian Cancer Cells.

Objectives: Mono(ADP-ribosyl)ation (MARylation), a post translational modification of proteins, is emerging as an important regulator of the biology of cancer cells. PARP7 (TiPARP), a mono (ADP-ribosyl) transferase (MART), MARylates its substrate α-tubulin in ovarian cancer cells, promoting destabilization of microtubules, cell growth, and migration. Recent development of RBN-2397, a potent inhibitor that selectively acts on PARP7, has provided a new tool for exploring the role of PARP7 catalytic activity in biological processes. In this study, we investigated the role of PARP7 catalytic activity in the regulation of ovarian cancer cell biology via MARylation of α-tubulin. Methods: Ovarian cancer cell lines (OVCAR4, OVCAR3) were treated with RBN-2397 and paclitaxel, both separately and in combination. Western blotting and immunoprecipitation confirmed the effects of RBN-2397 on α-tubulin MARylation and stabilization. Cell proliferation and migration were assessed, and α-tubulin stabilization was quantified using immunofluorescent imaging. RNA-sequencing was performed to assess the effects on gene expression changes. Results: RBN-2397 inhibited PARP7 activity, decreasing α-tubulin MARylation, leading to its stabilization, and reducing cancer cell proliferation and migration. The addition of paclitaxel further enhanced these effects, highlighting a synergistic interaction between the two drugs. Mutating the site of PARP7-mediated MARylation on α-tubulin similarly resulted in microtubule stabilization and decreased cell migration in the presence of paclitaxel. Conclusions: This study demonstrates that targeting PARP7 with RBN-2397, particularly in combination with paclitaxel, offers an effective strategy for inhibiting aggressive ovarian cancer cell phenotypes. Our findings underscore the potential of combining PARP7 inhibitors with established chemotherapeutics to enhance treatment efficacy in ovarian cancer.

Biological Functions and Therapeutic Potential of NAD+ Metabolism in Gynecological Cancers.

Nicotinamide adenine dinucleotide (NAD+) is an important cofactor for both metabolic and signaling pathways, with the dysregulation of NAD+ levels acting as a driver for diseases such as neurodegeneration, cancers, and metabolic diseases. NAD+ plays an essential role in regulating the growth and progression of cancers by controlling important cellular processes including metabolism, transcription, and translation. NAD+ regulates several metabolic pathways such as glycolysis, the citric acid (TCA) cycle, oxidative phosphorylation, and fatty acid oxidation by acting as a cofactor for redox reactions. Additionally, NAD+ acts as a cofactor for ADP-ribosyl transferases and sirtuins, as well as regulating cellular ADP-ribosylation and deacetylation levels, respectively. The cleavage of NAD+ by CD38-an NAD+ hydrolase expressed on immune cells-produces the immunosuppressive metabolite adenosine. As a result, metabolizing and maintaining NAD+ levels remain crucial for the function of various cells found in the tumor microenvironment, hence its critical role in tissue homeostasis. The NAD+ levels in cells are maintained by a balance between NAD+ biosynthesis and consumption, with synthesis being controlled by the Preiss-Handler, de novo, and NAD+ salvage pathways. The primary source of NAD+ synthesis in a variety of cell types is directed by the expression of the enzymes central to the three biosynthesis pathways. In this review, we describe the role of NAD+ metabolism and its synthesizing and consuming enzymes' control of cancer cell growth and immune responses in gynecologic cancers. Additionally, we review the ongoing efforts to therapeutically target the enzymes critical for NAD+ homeostasis in gynecologic cancers.

ADP-based fault-tolerant consensus control for multiagent systems with irregular state constraints.

This paper investigates the consensus control issue for nonlinear multiagent systems (MASs) subject to irregular state constraints and actuator faults using an adaptive dynamic programming (ADP) algorithm. Unlike the regular state constraints considered in previous studies, this paper addresses irregular state constraints that may exhibit asymmetry, time variation, and can emerge or disappear during operation. By developing a system transformation method based on one-to-one state mapping, equivalent unconstrained MASs can be obtained. Subsequently, a finite-time distributed observer is designed to estimate the state information of the leader, and the consensus control problem is transformed into the tracking control problem for each agent to ensure that actuator faults of any agent cannot affect its neighboring agents. Then, a critic-only ADP-based fault tolerant control strategy, which consists of the optimal control policy for nominal system and online fault compensation for time-varying addictive faults, is proposed to achieve optimal tracking control. To enhance the learning efficiency of critic neural networks (NNs), an improved weight learning law utilizing stored historical data is employed, ensuring the convergence of critic NN weights towards ideal values under a finite excitation condition. Finally, a practical example of multiple manipulator systems is presented to demonstrate the effectiveness of the developed control method.

The complex universe of inactive PARP1.

Poly(ADP-ribose) polymerase 1 (PARP1) is a crucial member of the PARP family, which modifies targets through ADP-ribosylation and plays key roles in a variety of biological processes. PARP inhibitors (PARPis) hinder ADP-ribosylation and lead to the retention of PARP1 at the DNA lesion (also known as trapping), which underlies their toxicity. However, inhibitors and mutations that make PARP1 inactive do not necessarily correlate with trapping potency, challenging the current understanding of inactivation-caused trapping. Recent studies on mouse models indicate that both trapping and non-trapping inactivating mutations of PARP1 lead to embryonic lethality, suggesting the unexpected toxicity of the current inhibition strategy. The allosteric model, complicated automodification, and various biological functions of PARP1 all contribute to the complexity of PARP1 inactivation.

Niraparib in Japanese patients with heavily pretreated, homologous recombination-deficient ovarian cancer: final results of a multicenter phase 2 study.

OBJECTIVE: To evaluate the long-term efficacy and safety of niraparib in Japanese women with heavily pretreated ovarian cancer. METHODS: This was the follow-up analysis of a phase 2, multicenter, open-label, single-arm study in Japanese women with homologous recombination-deficient, platinum-sensitive, relapsed, high-grade serous epithelial ovarian, fallopian tube, or primary peritoneal cancer who had completed 3-4 lines of chemotherapy and were poly(ADP-ribose) polymerase inhibitor naïve. Participants received niraparib (starting dose, 300 mg) once daily in continuous 28-day cycles until objective disease progression, unacceptable toxicity, or consent withdrawal. The primary endpoint was confirmed objective response rate (ORR), as assessed using Response Evaluation Criteria in Solid Tumors version 1.1. Safety evaluations included treatment-emergent adverse events (TEAEs). RESULTS: 20 patients were enrolled in the study and included in both efficacy and safety analyses. Median total study duration was 759.5 days. Median dose intensity was 201.3 mg/day. Confirmed ORR was 60.0% (90% confidence interval [CI]=39.4-78.3); 2 patients had complete response and 10 patients had partial response. Median duration of response was 9.9 months (95% CI=3.9-26.9) and the disease control rate was 90.0% (95% CI=68.3-98.8). The most common TEAEs were anemia (n=15), nausea (n=12), and decreased platelet count (n=11). TEAEs leading to study drug dose reduction, interruption, or discontinuation were reported in 16 (80.0%), 15 (75.0%), and 2 patients (10.0%), respectively. CONCLUSION: The long-term efficacy and safety profile of niraparib was consistent with previous findings in the equivalent population in non-Japanese patients. No new safety signals were identified. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03759600.

ADP-heptose attenuates Helicobacter pylori-induced dendritic cell activation.

Sophisticated immune evasion strategies enable Helicobacter pylori (H. pylori) to colonize the gastric mucosa of approximately half of the world's population. Persistent infection and the resulting chronic inflammation are a major cause of gastric cancer. To understand the intricate interplay between H. pylori and host immunity, spatial profiling was used to monitor immune cells in H. pylori infected gastric tissue. Dendritic cell (DC) and T cell phenotypes were further investigated in gastric organoid/immune cell co-cultures and mechanistic insights were acquired by proteomics of human DCs. Here, we show that ADP-heptose, a bacterial metabolite originally reported to act as a bona fide PAMP, reduces H. pylori-induced DC maturation and subsequent T cell responses. Mechanistically, we report that H. pylori uptake and subsequent DC activation by an ADP-heptose deficient H. pylori strain depends on TLR2. Moreover, ADP-heptose attenuates full-fledged activation of primary human DCs in the context of H. pylori infection by impairing type I IFN signaling. This study reveals that ADP-heptose mitigates host immunity during H. pylori infection.

The quest to identify ADP-ribosylation readers: methodological advances.

ADP-ribosylation regulates numerous fundamental cellular processes in health and disease. However, the limited availability of suitable tools and methods prevents the identification and characterization of certain components of the ADP-ribosylation signaling network and, consequently, efficient utilization of their biomedical potential. Identification of ADP-ribose (ADPr) readers has been particularly impeded by challenges associated with the development of ADPr-based enrichment probes. These difficulties were finally overcome in several recent studies describing various approaches to identifying ADPr readers in an unbiased, proteome-wide manner. In this review we discuss these different strategies and their limitations, benefits and drawbacks, and summarize how these technologies contribute to a dissection of ADP-ribosylation signaling networks. We also address unmet technological needs and future directions to investigate interactions with ADPr linkages.

Efficacy and safety of rucaparib in patients with recurrent high-grade ovarian carcinoma: A systematic review and meta-analysis.

Ovarian cancer stands as the third most prevalent gynecological malignancy. The advent of PARP inhibitors, particularly rucaparib, has revolutionized the landscape of advanced ovarian cancer treatment, demonstrating notable efficacy with minimal toxicity, especially in patients not previously exposed to PARP inhibitors. Rucaparib's precision-driven approach, targeting specific genetic mutations, disrupts DNA repair mechanisms, resulting in cytotoxic effects on neoplastic cells. This comprehensive review delves into the clinical efficacy and safety profile of rucaparib in recurrent ovarian cancer, showcasing its promising therapeutic approach. A systematic search of studies reporting rucaparib efficacy and safety, up to September 2023, was conducted across various reputable databases and sources. The meta-analysis of seven articles revealed a pooled objective response rate (ORR) of 0.331 (95% CI, 0.221-0.449; I2 = 92.4%), underscoring rucaparib's efficacy, particularly evident in the BRCA-mutated cohort. Rucaparib consistently outperformed controls in progression-free survival (PFS) and overall survival (OS). Safety evaluations indicated that 98.7% of patients experienced treatment-emergent adverse events (TEAEs), with 61% being grade ≥3. Notable TEAEs included nausea (69.0%), fatigue (66.8%), vomiting (37.3%), and constipation (32.1%). Hematological concerns comprised anemia (47.9%), thrombocytopenia, elevated AST/ALT (37.3%), and serum creatinine levels (19.7%). Despite favourable outcomes, the rucaparib group recorded higher event rates across various metrics than controls. The findings underscore the need for meticulous monitoring and dose adjustments to optimize therapeutic outcomes and mitigate the increased risks associated with adverse events. International Prospective Register of Systematic Review Identifier: CRD42023459646.

Liposome preparation of alpha-arbutin: stability and toxicity assessment using mouse B16F10 melanoma cells.

Melanoma is the most aggressive type of skin cancer, with few therapeutic alternatives following metastasis development. In recent years, drug delivery-associated nanotechnology has shown promising targeted results with diminished adverse effects compared to conventional treatments. This study aimed to (1) examine the effects of plant-derived α-arbutin, a natural compound and (2) compare these findings with bioactively developed liposomes containing α-arbutin utilizing the B16-F10 murine melanoma cell line as a model. Liposomes were obtained through reversed-phase evaporation by applying a spray dryer to assess their stability. The following biologic assays were measured cytotoxicity/antiproliferative (MTT, Neutral Red, and dsDNA PicoGreen). In addition, the levels of melanin and purinergic enzymes were also measured. The production of reactive oxygen species (ROS) and nitric oxide (NO) was determined as a measure of oxidative state. Treatment with nano-liposome containing alpha-arbutin induced a significant 68.4% cytotoxicity, similar to the positive control, in the B16-F10 murine melanoma cell line at 72 hr. Further, arbutin and liposomes containing alpha-arbutin increased levels of ROS and nitrite formation at 72 hr at the highest concentration (100 and 300 µg/ml) of treatments. Arbutin and liposomes containing alpha-arbutin reduced melanin levels at all tested concentrations. In addition, arbutin and alpha-arbutin containing liposomes lowered nucleotides (AMP, ADP, and ATP) and nucleoside (adenosine) levels in melanoma cells. Evidence suggests that α-arbutin containing liposome can be considered as an alternative immunosuppressive agent stimulated in melanoma treatment.

Disruption of Poly(ADP-ribosyl)ation Improves Plant Tolerance to Methyl Viologen-Mediated Oxidative Stress via Induction of ROS Scavenging Enzymes.

ADP-ribosylation (ADPRylation) is a mechanism which post-translationally modifies proteins in eukaryotes in order to regulate a broad range of biological processes including programmed cell death, cell signaling, DNA repair, and responses to biotic and abiotic stresses. Poly(ADP-ribosyl) polymerases (PARPs) play a key role in the process of ADPRylation, which modifies target proteins by attaching ADP-ribose molecules. Here, we investigated whether and how PARP1 and PARylation modulate responses of Nicotiana benthamiana plants to methyl viologen (MV)-induced oxidative stress. It was found that the burst of reactive oxygen species (ROS), cell death, and loss of tissue viability invoked by MV in N. benthamiana leaves was significantly delayed by both the RNA silencing of the PARP1 gene and by applying the pharmacological inhibitor 3-aminobenzamide (3AB) to inhibit PARylation activity. This in turn reduced the accumulation of PARylated proteins and significantly increased the gene expression of major ROS scavenging enzymes including SOD (NbMnSOD; mitochondrial manganese SOD), CAT (NbCAT2), GR (NbGR), and APX (NbAPX5), and inhibited cell death. This mechanism may be part of a broader network that regulates plant sensitivity to oxidative stress through various genetically programmed pathways.

A molten globule ensemble primes Arf1-GDP for the nucleotide switch.

The adenosine di-phosphate (ADP) ribosylation factor (Arf) small guanosine tri-phosphate (GTP)ases function as molecular switches to activate signaling cascades that control membrane organization in eukaryotic cells. In Arf1, the GDP/GTP switch does not occur spontaneously but requires guanine nucleotide exchange factors (GEFs) and membranes. Exchange involves massive conformational changes, including disruption of the core ß-sheet. The mechanisms by which this energetically costly switch occurs remain to be elucidated. To probe the switch mechanism, we coupled pressure perturbation with nuclear magnetic resonance (NMR), Fourier Transform infra-red spectroscopy (FTIR), small-angle X-ray scattering (SAXS), fluorescence, and computation. Pressure induced the formation of a classical molten globule (MG) ensemble. Pressure also favored the GDP to GTP transition, providing strong support for the notion that the MG ensemble plays a functional role in the nucleotide switch. We propose that the MG ensemble allows for switching without the requirement for complete unfolding and may be recognized by GEFs. An MG-based switching mechanism could constitute a pervasive feature in Arfs and Arf-like GTPases, and more generally, the evolutionarily related (Ras-like small GTPases) Rags and Gα GTPases.

Mechanism of PARP1 Elongation Reaction Revealed by Molecular Modeling.

Poly(ADP-ribose) polymerase 1 (PARP1) plays a major role in the DNA damage repair and transcriptional regulation, and is targeted by a number of clinical inhibitors. Despite this, catalytic mechanism of PARP1 remains largely underexplored because of the complex substrate/product structure. Using molecular modeling and metadynamics simulations we have described in detail elongation of poly(ADP-ribose) chain in the PARP1 active site. It was shown that elongation reaction proceeds via the SN1-like mechanism involving formation of the intermediate furanosyl oxocarbenium ion. Intriguingly, nucleophilic 2'A-OH group of the acceptor substrate can be activated by the general base Glu988 not directly but through the proton relay system including the adjacent 3'A-OH group.

Pancreatic ß­cell apoptosis in type 2 diabetes is related to post­translational modifications of p53 (Review).

Pancreatic ß­cells are the only cells that synthesize insulin to regulate blood glucose levels. Various conditions can affect the mass of pancreatic ß­cells and decrease insulin levels. Diabetes mellitus is a disease characterized by insulin resistance and chronic hyperglycemia, mainly due to the loss of pancreatic ß­cells caused by an increase in the rate of apoptosis. Additionally, hyperglycemia has a toxic effect on ß­cells. Although the precise mechanism of glucotoxicity is not fully understood, several mechanisms have been proposed. The most prominent changes are increases in reactive oxygen species, the loss of mitochondrial membrane potential and the activation of the intrinsic pathway of apoptosis due to p53. The present review analyzed the location of p53 in the cytoplasm, mitochondria and nucleus in terms of post­translational modifications, including phosphorylation, O­GlcNAcylation and poly­ADP­ribosylation, under hyperglycemic conditions. These modifications protect p53 from degradation by the proteasome and, in turn, enable it to regulate the intrinsic pathway of apoptosis through the regulation of anti­apoptotic and pro­apoptotic elements. Degradation of p53 occurs in the proteasome and depends on its ubiquitination by Mdm2. Understanding the mechanisms that activate the death of pancreatic ß­cells will allow the proposal of treatment alternatives to prevent the decrease in pancreatic ß­cells.

Efficacy and safety of PARPis combined with an ICIs for advanced or metastatic triple-negative breast cancer: a single-arm meta-analysis.

Although the intervention for triple-negative breast cancer (TNBC) patients has improved and survival time has increased, the combination of immune checkpoint inhibitors(ICIs) and PARP inhibitors (Poly ADP-Ribose Polymerase inhibitors, PARPis) is still controversial. Previous studies revealed that the combined use of ICIs and PARPis led to increased antitumor activity. However, most of these combined regimens are nonrandomized controlled trials with small sample sizes. The purpose of this meta-analysis was to evaluate the efficacy and safety of ICIs combined with PARPis in patients with advanced or metastatic TNBC. The PubMed, Embase, Cochrane Library and Web of Science databases were systematically searched. The results including the objective remission rate (ORR), disease control rate (DCR), progression-free survival (PFS) and adverse events (AEs), were subjected to further analysis. Four studies involving 110 subjects were included in this meta-analysis. The combined ORR and DCR were 23.6% and 53.6%, respectively; while the ORR and DCR of BRCAmut patients were 38.1% and 71.4%, respectively. The median PFS of the patients was 4.29 months. As for safety, the most common AEs were nausea (49.0%), anemia (44.3%) and fatigue (40.6%). Most of them were grade 1 or 2, and the incidence of adverse events ≥ III was obviously low. Except for anemia, the incidence of AEs ≥ III was < 10%. This meta-analysis revealed that the combination of ICIs and PARPis has good efficacy and safety for advanced or metastatic TNBC patients.

Clinicopathological and molecular features of tubo-ovarian carcinosarcomas: a series of 51 cases.

Objective: Tubo-ovarian carcinosarcomas are rare, extremely aggressive malignant tumors that contain both carcinomatous and sarcomatous components. Due to the disease's rarity, developing an effective treatment strategy for ovarian carcinosarcomas has been challenging. A study was conducted to investigate the clinicopathologic and molecular features of this rare disease. Methods: We enrolled all patients diagnosed with tubo-ovarian carcinosarcomas from January 2007 to December 2022. The clinical and pathological data were gathered from medical records. Kaplan-Meier curves were plotted to calculate OS and PFS. The Log-rank test and Cox regression model were utilized to explore the relationship between clinicopathological parameters and survival. Patients with cancer tissues available had sequencing with a 242-gene panel done to investigate the mutational landscape and signature of the disease. Results: In total, 65% of the patients were diagnosed with advanced-stage cancer. The median PFS and OS of this cohort were 27 and 40 months, respectively, and there was no significant difference in survival between the homologous and heterologous components of sarcoma. Unexpectedly, staging did not have effects on prognosis. All patients had surgical attempts, and suboptimal debulking status was correlated with poorer PFS and OS. MSI was identified in 0% with low Tumor mutation burden (TMB) indicating a poor response to immunotherapy. Low HER2 expression is controversial, according to previous reports, and gives us limited choices with this rare and aggressive disease. We surprisingly found the homologous recombination deficiency (HRD)-positive status was identified in 64% of OCS, which is significantly higher than UCS and other types of epithelial ovarian cancer. The fact that all patients in our cohort who received olaparib as maintenance therapy had survived over 30 months and two had no evidence of recurrence at the latest follow-up might further validate the role of poly (ADP-ribose) polymerase inhibitors (PARPi) in the management of OCS. Conclusion: OCS patients seemed to respond to carboplatin/paclitaxel with optimal PFS and OS. Cytoreduction with no residuals proved to be the sole independent prognostic factor. WES should be done to assess the prognosis and assist with the targeted therapy, especially the HRD test, which might help select potential patients who benefit from PARPi.

Electrochemical detection of poly(ADP-ribose) polymerase-1 with silver nanoparticles as signal labels by integrating the advantages of homogeneous reaction with surface-tethered detection.

Poly(ADP-ribose)polymerase-1 (PARP1) could be activated by binding to nucleic acids with specific sequences, thus catalyzing the poly-ADP-ribosylation (PARylation) of target proteins including PARP1 itself. Most of the previously reported electrochemical methods for the determination of PARP1 were relied on the electrostatic interactions, which required the pre-immobilization of DNA on an electrode for the capture of PARP1. Herein, we reported an "immobilization-free" electrochemical strategy for the assays of PARP1 on the basic of avidin-biotin interaction. Once PARP1 was activated by binding with the specific double-stranded DNA (dsDNA) in a homogeneous solution, the biotinylated nicotinamide adenine dinucleotide (biotin-NAD+) was transferred onto PARP1, resulting in the formation of biotinylated PAR polymers. The resulting biotinylated PAR polymers were then captured by a neutravidin (NA)-modified electrode through avidin-biotin interactions. The rich biotin moieties in the PAR polymers allowed for the capture of NA-modified silver nanoparticles (NA-AgNPs) through the avidin-biotin interactions. The surface-tethered AgNPs produced a well-defined electrochemical signal due to the characteristic solid-state Ag/AgCl process. The "immobilization-free", electrostatic interaction-independent electrochemical biosensor exhibited low background current, high sensitivity, and good stability. It has achieved the determination of PARP1 with a detection limit down to 0.7 mU. The biosensor was further applied to determine the inhibition efficiency of potential inhibitors with a satisfactory result. This method shows promising potential applications in PARP1-related clinical diagnosis and drug discovery.

Poly-ADP-ribosylation dynamics, signaling, and analysis.

ADP-ribosylation is a reversible post-translational modification that plays a role as a signaling mechanism in various cellular processes. This modification is characterized by its structural diversity, highly dynamic nature, and short half-life. Hence, it is tightly regulated at many levels by cellular factors that fine-tune its formation, downstream signaling, and degradation that together impacts cellular outcomes. Poly-ADP-ribosylation is an essential signaling mechanism in the DNA damage response that mediates the recruitment of DNA repair factors to sites of DNA damage via their poly-ADP-ribose (PAR)-binding domains (PBDs). PAR readers, encoding PBDs, convey the PAR signal to mediate cellular outcomes that in some cases can be dictated by PAR structural diversity. Several PBD families have been identified, each with variable PAR-binding affinity and specificity, that also recognize and bind to distinct parts of the PAR chain. PARylation signaling has emerged as an attractive target for the treatment of specific cancer types, as the inhibition of PAR formation or degradation can selectively eliminate cancer cells with specific DNA repair defects and can enhance radiation or chemotherapy response. In this review, we summarize the key players of poly-ADP-ribosylation and its regulation and highlight PBDs as tools for studying PARylation dynamics and the expanding potential to target PARylation signaling in cancer treatment.

Injection of Adipose-Derived Mesenchymal Stem/Stromal Cells Suppresses Muscle Atrophy Markers and Adipogenic Markers in a Rat Fatty Muscle Degeneration Model.

Fatty muscle degeneration and muscle atrophy have not been successfully treated due to their irreversible pathology. This study evaluated the efficacy of rat adipose-derived mesenchymal stem/stromal cells (ADP MSCs) in treating fatty muscle degeneration (FD). A total of 36 rats were divided into three groups: the control (C) group (n = 12); FD model group, generated by sciatic nerve crushing (n = 12); and the group receiving ADP MSC treatment for FD (FD+MSCs) (n = 12). In Group FD+MSCs, ADP MSCs were injected locally into the gastrocnemius muscle one week after the FD model was created (Day 8). On Day 22 (n = 18) and Day 43 (n = 18), muscle morphology, histopathology, and molecular analyses (inflammation, muscle atrophy, adipocytes, and muscle differentiation markers) were performed. In Group FD+MSCs, the formation of immature myofibers was observed on Day 22, and mitigation of fatty degeneration and muscle atrophy progression was evident on Day 43. Gene expression of muscle atrophy markers (FBXO32, TRIM63, and FOXO1) and adipogenic markers (ADIPOQ, PPARG, FABP4, and PDGFRA) was lower in Group FD+MSCs than Group FD on Day 43. ADP MSCs induce anti-inflammatory effects, inhibit fat accumulation, and promote muscle regeneration, highlighting their potential as promising therapy for FD and atrophy.